Centromere identity in Drosophila is not determined in vivo by replicationtiming

Citation
B. Sullivan et G. Karpen, Centromere identity in Drosophila is not determined in vivo by replicationtiming, J CELL BIOL, 154(4), 2001, pp. 683-690
Citations number
34
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
JOURNAL OF CELL BIOLOGY
ISSN journal
0021-9525 → ACNP
Volume
154
Issue
4
Year of publication
2001
Pages
683 - 690
Database
ISI
SICI code
0021-9525(20010820)154:4<683:CIIDIN>2.0.ZU;2-R
Abstract
Centromeric chromatin is uniquely marked by the centromere-specific histone CENP-A. For assembly of CENP-A into nucleosomes to occur without competiti on from H3 deposition, it was proposed that centromeres are among the first or last sequences to be replicated. In this study, centromere replication in Drosophila was studied in cell lines and in larval tissues that contain minichromosomes that have structurally defined centromeres. Two different n ucleotide incorporation methods were used to evaluate replication timing of chromatin containing CID, a Drosophila homologue of CENP-A. Centromeres in Drosophila cell lines were replicated throughout S phase but primarily in mid S phase. However, endogenous centromeres and X-derived minichromosome c entromeres in vivo were replicated asynchronously in mid to late S phase. M inichromosomes with structurally intact centromeres were replicated in late S phase, and those in which centric and surrounding heterochromatin were p artially or fully deleted were replicated earlier in mid S phase. We provid e the first in vivo evidence that centromeric chromatin is replicated at di fferent times in S phase. These studies indicate that incorporation of CID/ CENP-A into newly duplicated centromeres is independent of replication timi ng and argue against determination of centromere identity by temporal seque stration of centromeric chromatin replication relative to bulk genomic chro matin.